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Psychopharmacology | Lab Members

Matthew Clasen

Matthew Clasen 

Curriculum Vitae


I am a second-year PhD student in Dr. Anthony L. Riley’s Psychopharmacology Laboratory at American University. My primary research interests revolve around understanding the neurobiological substrates mediating the aversive effects of drugs of abuse and in turn assessing how manipulating those substrates alters their affective properties. 

As a second year doctoral candidate in the Behavior, Cognition, and Neuroscience program, I have been heavily involved in multiple research projects and have recently and successfully defended my master’s thesis, “Adolescent Rats Display Attenuated Taste Avoidance Learning Relative to Adults and Fail to Demonstrate a US Pre-exposure Effect”. The results of my Master’s Thesis research substantiates past research which suggests that adolescents demonstrate attenuated taste avoidance learning relative to adults and further demonstrated that adolescents were unable to produce US pre-exposure effect under our experimental parameters. Currently, I am assessing the generalization of my master’s thesis results by testing whether adolescents are capable of demonstrating US pre-exposure effects to cocaine and morphine. 

In addition to exploring the US pre-exposure effect within adolescence, I am also implementing the use of the novel Chemogenic tool, DREADDs, to both artificially induce a CTA response by increasing excitatory GPCR (G Protein Coupled Receptor) activity in brainstem nuclei, and inhibit the development of CTA responses induced by common drugs of abuse like cocaine and heroin, by exciting inhibitory GPCR activity. Work from our laboratory and others suggest that the overall affective response to a drug (and its potential for use and abuse) is thought to reflect the balance between the rewarding and aversive properties of that drug. Specifically, the aversive properties of drugs limit drug use and the rewarding properties maintain it. Given this balance, if we were to understand what neural pathways mediate the aversive properties of drugs of abuse, potential therapies could target these systems to increase the aversive properties of drugs to decrease their abuse potential.